Work is now underway to develop microfluidic devices for analyzing chemical or biological fluids. A “microfluidic” device typically includes fluid channels having microscale dimensions. For example, a fluid channel in a typical microfluidic device may have a width of less than about 1000 microns.
In a typical application for a microfluidic device, a fluid containing a chemical compound may flow towards a reaction site on the microfluidic device. At the reaction site, the fluid may contact another fluid containing a different substance. The characteristics of the resulting fluid passing downstream of the reaction site may be detected to determine if the chemical compound reacts with the substance. The characteristics of the fluid may correspond to, for example, the concentration of the chemical compound in the fluid stream. If the concentration of the chemical compound in the fluid passing downstream of the reaction site is lower than the concentration of the chemical compound upstream of the reaction site, then it is likely that the chemical compound reacts with the substance.
Microfluidic analytical systems have a number of advantages over other types of analytical systems. For example, microfluidic systems are particularly well suited for analyzing or reacting samples with low volumes. In a typical microfluidic system, samples on the order of nanoliters or even picoliters can be reacted or analyzed. Because of the small volumes of fluids being handled, microfluidic analytical systems may be used to rapidly assay large numbers of samples. The assays can be performed to study the effect of numerous compounds in various biological processes. For example, test compounds that may block, reduce, or enhance the interactions between different biological molecules, such as a receptor molecule and a corresponding ligand, may be identified as potential candidate drugs.
In recent years, the number of test compounds produced by modern combinatorial chemistry techniques has dramatically increased. While conventional microfluidic systems can be used to test the increasing number of compounds, the throughput of such systems could be improved. There is a continuing need to screen large numbers of samples quickly and accurately.
Embodiments of the invention address this and other problems.